To assess endocrine changes in midlife women, the University of Michigan's Central Ligand Assay Satellite Services (CLASS) laboratory will continue to support the Study of Women's Health Across the Nation (SWAN). We will use state-of-the-science, automated assays for all the major reproductive axis hormones (i.e., LH, FSH, estradiol, progesterone, and testosterone), adrenal markers of aging (DHEAS), other endocrine markers (TSH, sex hormone binding globulin {SHBG}) and new ovarian markers which have the potential to allow us to hormonally define the menopausal transition and the postmenopause with greater precision (inhibin A and B, estrone). In order to continue to support the Daily Hormone Study (DHS), CLASS will complete development and utilize sensitive and specific urinary assays for LH, FSH and the principal urinary metabolites of estradiol and progesterone, estrone conjugates and pregnanediol glucuronide, respectively. Our specific goals for the proposed project period are to: 1) utilize, implement and develop state-of-the-science, reliable, precise and cost-effective analytical methods that meet all study needs (analyte selection, limits of detection, range of performance), minimize variability, provide long-term stability and maximize reliability; 2) incorporate quality assurance procedures that minimize error and variability as assessed by rigorous quality control procedures; 3) utilize and develop additional electronic data handling and analysis procedures that, in addition to reducing labor costs, minimize the need for manual intervention and nearly eliminate the possibility of errors; 4) utilize sample labeling and handling systems that ensure continuous association between a labeled sample and data identified with the tube while maximizing the likelihood that the integrity of a sample is preserved unmodified; and 5) develop a temporary storage repository. In this manner, we will continue to play a key role in the advancement of the scientific goals of the parent SWAN study.